The first surprise is that Michele Roberts has swapped her house in Holloway, full of colourful clutter and a sense of benign decay, for a compact City pied-a-terre in a gleaming modern block a stone's throw from the Bank of England. Even the lilies in the vase match the white walls and cream furniture. We drink white wine, too, but Roberts is quick to point out the red wine stains on the carpet from a recent party. Hedonism has not yet been expunged from the life of this writer whose main concerns, expressed in the title of her collected essays, are "Food, Sex and God".

Food is still a central pleasure and a theme of almost pornographic sensuality in her work; but she's slimmer than when I last saw her. These days, she keeps an eye on her weight and swims every day. Michele Roberts is nearly 50, and she is glowing. Suspicious of new technology, she has finally swapped her Olivetti, with its bouncy keys "like little finger-tip trampolines" for a word-processor ("I always want to call it a food-processor!") and found that her almost superstitious fear of losing the writing ritual evaporated. "It was like a new seduction," she laughs, "a better machine, a better lover, better technique..."

The move to minimalism has more than a little to do with the fact that her stepsons are now old enough to flee the nest. If Roberts has chucked out her chintz and most of her books and furniture, it is only as far as her house in Normandy, where she spends "about 60 per cent" of her time and does most of her writing. It is, however, difficult to resist a feeling that there has been some serious streamlining and radical change, particularly in the light of the biggest surprise of all. Her new novel, Fair Exchange (Little, Brown, pounds 15.99), set at the time of the French Revolution, is a rollicking good read with not a nun in sight.

Michele Roberts without Catholicism would, one imagines, be a little like Woody Allen without neurosis. Since her first novel, A Piece of the Night, in 1978, she has explored the world of catechisms and convents, visions and Virgins, sex and sin, with lush detail and passionate intensity. Her female characters exhibit a lust for life that they find impossible to square with their Catholic roots, a tension that has led to wild flights of surrealism. This culminated in her previous novel, Impossible Saints, a subversively playful collection of fables, bursting with madonnas and whores, dismemberment and incest.

Fair Exchange seems an infinitely calmer affair. Split, like Roberts, between London and Normandy, it tells the tale of two young women, one French, the other a pupil of Mary Wollstonecraft, who discover love, motherhood and independence against a background of revolution. Both grapple with the scandal of extra-marital pregnancy, a dawning feminist consciousness and, as in all good page-turners, a secret. There's still a sense of play, with shades of Jane Eyre and Angela Carter, but it all feels very much less self-consciously clever than her recent work. Calvino and Kristeva seem to have receded and the Marquis de Sade replaced, dare I say it, by Georgette Heyer. Is this fair?

"Yes, I think in a playful way I wanted to come out and say I've read a lot of her stuff and I really have loved it... I think it's going to appeal to people who like stories, who aren't frightened by romance as a form and who don't expect everything to be very clever and lofty." Certainly, there's a new lightness of touch, a sense of maternal presence to replace the familiar theme of maternal absence - and a conspicuous lack of Catholic guilt. "I felt that having written eight novels which scoured out my soul and my unconscious, it would be fun to write something a little more light- hearted. I killed off some old demons in Impossible Saints and solved something about Catholicism and why I'd found it so damaging".

There is, she points out, an ex-convent: a joke for her husband, Jim, who announced firmly after the last book, "Mimi, I think you've done enough nuns". Roberts has not, however, thrown out the baby with the bath-water. She now believes that "God is immanent... like a shorthand for the connection between people and things and the world".

It's something of a relief to hear that she's "not into Goddess", since the brand of feminism that surfaced in her early work is sometimes associated with the crude Jungian archetypes appropriated by New Age types in tie- dye pantaloons. She is still intrigued and inspired by Jung, but thinks that he was "probably a randy old bugger who fucked all the women and then told them off for having an animus problem". Dreams, usually a central part of her writing experience, featured less this time, and even the genesis of the novel was different.

In the past, her novels have started as a haunting image, but this one was the idea of her French publisher. "We were having lunch in Paris one day and he said `Hey, I've got a novel for you to write'". Roberts immediately knew that this period, of incipient feminism and political radicalism, was her opportunity to "grapple with what we went through in the Seventies" - a novel she had wanted to write for five years.

It all sounds considerably less angst- ridden than her previous work. "I think I'm in a happier, more contented state of being". Domestic happiness (she and Jim have been together for 11 years), Catholic catharsis and literary acclaim seem to have created a calmer climate in which she is free to explore the power of storytelling. She was, when she was small, the family storyteller, but it was an impulse she learnt to suppress as she adapted to "someone else's story, a story told by the Catholic Church". "Now I feel I can sit on top of the story," she announces. "It's like sitting on your mountain and thinking I can walk around this mountain any way I want".

If Roberts has learnt to demystify fiction, writing poetry remains for her "almost like a religious experience". She has talked before of "the utterance of poetic language as a feminine pleasure recalling the baby's blissful babble at the maternal breast". How far does this relate to her own poetry? "I do feel that there's something quite basic going on," she agrees, "which is a need to speak from the unconscious". She has published three collections of poetry, but confesses that she is "in a real crisis" about it. Her poems are, like her fiction, passionate, exuberant and sensual, but they are not "what the people in power like... My poetry is not establishment poetry".

Perhaps not, but her status leans more towards the establishment than away from it these days. She has been shortlisted for the Booker, won the W H Smith award, does regular tours for the British Council and is an occasional presenter for Radio 3. In the chic flat overlooking the Thames, the years of sleeping in coats in cold squats and living on peanut butter and carrots seem far away. Her anger has dissipated a little, her frustration softened by "ordinary happiness", but her passion remains as strong as ever. "I feel I wasted a lot of my precious youth and my thirties sorrowing and suffering," she laments. "I love meeting new people, I love conversations, I love food, I love sex and I love wine... I've always been greedy for life, but I think I was so fraught about it I wasn't always enjoying it".

Duality is a constant theme in the work of this writer, who is half-French, half- English, and a twin to boot. It is a theme that she seems to be acting out in a polarised double life. In London, she sips wine at literary parties and looks after the public side of her life as a writer. In France, she writes like a demon, cooks delicious meals, digs the garden and chats to the neighbours about vegetables, pigs and the weather. "There's a bit of me," says sleek Michele Roberts on the elegant cream sofa, "that really likes walking about grunting".

Michele Roberts, a biography

Michele Roberts was born in 1949 to a French mother and an English father and brought up in Edgware. After a convent-school education, she read English at Oxford, where she became a founder member of the first women's street-theatre group. During the Seventies, she was a pregnancy counsellor, a librarian, a hippie, a lesbian, a feminist activist and the poetry editor of Spare Rib. Her first novel, A Piece of the Night, was published to great acclaim in 1978, followed by The Visitation (1983) and The Wild Girl (1984), a controversial fictionalised account of the life of Mary Magdalen. She has published five other novels including Flesh and Blood (1994), which provoked comparisons with Woolf, Colette and Joyce, and Daughters of the House (1992), shortlisted for the Booker and winner of the WH Smith Literary Award. Her other publications include a collection of short stories, a book of essays (Food, Sex and God) and three collections of poetry. She is married to the artist Jim Latter.